body {
  width: 100%;
  min-width: 320px;
  max-width: 640px;
  margin: 0 auto;
  font-size: 14px;
  font-family: -apple-system, Helvetica, sans-serif;
  color: #666;
  line-height: 1.5;
  /* background-color: #ccc; */
}

.clearfix:after {
  content: '';
  display: block;
  height: 0;
  clear: both;
  visibility: hidden;
}

* {
  /* 清除点击高亮 */
  -webkit-tap-highlight-color: transparent;
}

input {
  /* IOS 清除原有的样式（才可以自定义样式？） */
  -webkit-appearance: none;
  appearance: none;
}

img,
a {
  /* 禁用长按页面弹出菜单 */
  -webkit-touch-callout: none;
}

ul {
  margin: 0;
  padding: 0;
  list-style: none;
}

img {
  /* 去除图片顶部空白缝隙 */
  vertical-align: top;
}

div {
  box-sizing: border-box;
}

a {
  color: #666;
  text-decoration: none;
}

/* app（页面顶部盒子） */

.app {
  height: 45px;
}

.app ul li {
  float: left;
  height: 45px;
  background-color: #333;
  text-align: center;
  line-height: 45px;
  color: #fff;
}

.app ul li:nth-child(1) {
  width: 8%;
}

.app ul li:nth-child(1) img {
  width: 8px;
  /* 注！图片和文字居中对齐 */
  vertical-align: middle;
}

.app ul li:nth-child(2) {
  width: 10%;
}

.app ul li:nth-child(2) img {
  width: 30px;
  /* 注！图片和文字居中对齐 */
  vertical-align: middle;
}

.app ul li:nth-child(3) {
  width: 57%;
}

.app ul li:nth-child(4) {
  width: 25%;
  background-color: #f63515;
}

/* 搜索 */

.search-wrap {
  position: fixed;
  height: 44px;
  width: 100%;
  min-width: 320px;
  max-width: 640px;
  /* 注！解决外边距合并的问题 */
  overflow: hidden;
}

.search-btn {
  position: absolute;
  top: 0;
  left: 0;
  width: 40px;
  height: 44px;
}

.search-btn::before {
  content: '';
  display: block;
  width: 20px;
  height: 18px;
  background: url(../images/s-btn.png) no-repeat;
  background-size: 20px 18px;
  margin: 14px 0 0 15px;
}

.search-login {
  position: absolute;
  top: 0;
  right: 0;
  width: 40px;
  height: 44px;
  color: #fff;
  line-height: 44px;
}

.search {
  position: relative;
  height: 30px;
  background-color: #fff;
  margin: 0 50px;
  border-radius: 15px;
  margin-top: 7px;
}

.jd-icon {
  position: absolute;
  width: 20px;
  height: 15px;
  top: 8px;
  left: 12px;
  background: url(../images/jd.png) no-repeat;
  background-size: 20px 15px;
}

.jd-icon::after {
  position: absolute;
  content: '';
  top: 0;
  right: -8px;
  display: block;
  width: 1px;
  height: 15px;
  background-color: #ccc;
}

.sou {
  position: absolute;
  top: 8px;
  left: 50px;
  width: 18px;
  height: 15px;
  /* 注！二倍精灵图 */
  /* 坐标是精灵图缩小一倍时图标的坐标 */
  background: url(../images/jd-sprites.png) no-repeat -81px 0;
  /* 尺寸是精灵图缩小后的尺寸 */
  background-size: 200px auto;
}

/* 主体内容 */

.slider img {
  width: 100%;
}

.brand {
  overflow: hidden;
  border-radius: 10px 10px 0 0;
}

.brand div {
  float: left;
  width: 33.33%;
}

.brand div img {
  width: 100%;
}

/* nav 部分 */

nav {
  padding-top: 5px;
}

nav a {
  float: left;
  /* 添加浮动后，无需将 a 转为行内块 */
  width: 20%;
  text-align: center;
}

nav a img {
  width: 40px;
  margin: 10px 0;
}

nav a span {
  display: block;
}

/* 新闻模块 */

.news {
  margin-top: 5px;
}

.news a {
  float: left;
  /* 为 a 元素添加 CSS3 盒子模型属性，防止添加边框时撑开 */
  box-sizing: border-box;
}

.news img {
  width: 100%;
}

.news a:nth-child(1) {
  width: 50%;
}

.news a:nth-child(n+2) {
  width: 25%;
  border-left: 1px solid #ccc;
}